A general solution for the input reflection coefficient of a mismatched 4-port coaxial junction, obtained by the use of the S-matrix renormalisation technique, is applied to the symmetrical 4-port coaxial junction, whereby three known 1-port standards can be connected in parallel to generate complex standards of immittance or reflection coefficients for the calibration of immittance bridges, refle...
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The directivity/noise-temperature ratio of aperture antennas, which is expressed as a ratio of two Hermitian quadratic forms, is maximised by using computer techniques. The design parameter v0 is introduced for the purpose of determining the noisefree angular region in which it is desired to confine the radiated energy. By the choice of a ficticious noise-temperature distribution, it is intended t...
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A computer program CIRFER is described that facilitates the design of circulators on all-ferrite substrates. With the use of the design approach, J-band circulators have been fabricated using thin-film techniques on ferrite substrates of different 4π8 values. Good agreement was obtained between theoretical and experimental resonant-disc diameters at the centre frequency of opera...
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In this paper, the method of Green's function and operator technique is used to find the solution of the field equations of overhead and underground transmission lines in the presence of a semi-infinite N-layer non-perfect conducting earth. The solution gives an explicit analytical expression of the field in any of the layers produced by a line current located in a given layer. The expression invo...
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Using as a reference the single-phase fast-decoupled algorithm, this paper describes the modifications required to produce an efficient three-phase fast-decoupled load flow. The compound-coil concept is used in the representation of power-system components, and the effect of automatic voltage regulators is modelled as part of the reactive-power Jacobian-matrix equation. It is shown that the three-...
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When a 6 -thyristor a.c. regulator feeds a balanced load characterised by constants R or RL or RC, three distinct operating modes can successively be found when delay angle increases: (a) 3 or 2 conducting rectifiers, (b) 2 conducting rectifiers, (c) 2 or 0 conducting rectifiers. In the paper we define the areas corresponding to these three operating modes.
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Schemes based on synchronous generators and high-voltage d.c. transmission are often used to exploit remote natural energy resources. However, unless the provision of synchronous power at the sending end is essential, such schemes are unnecessarily complex. The paper describes an alternative solution using self-excited induction-generator/controlled-rectifier units, which eliminate the problems of...
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Fourier-transform theory is used to solve the longitudinal-edge-effect problem in linear induction motors, for constant-current conditions. Inversion of the Fourier transform is obviated by employing Parseval's theorem; calculations are thus considerably simplified. Experimental confirmation is given, together with an approximate method for sketching the thrust/slip curve. The ratio (goodness fact...
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A new brushless excitation system is described for a synchronous motor such as may be used in some forms of variable-frequency inverter-fed drive with rotor-angle control. Transformer primary and secondary windings are incorporated in the stator and rotor, respectively, and the latter winding feeds the field winding via a bridge-rectifier circuit. The transformer primary winding is connected in a ...
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The initial expansion of the leader channel and its subsequent cooling have been investigated in 10Â¿30cm rod-plane gaps in air using a high-speed schlieren technique. The channel was found to expand to a maximum value of 0.6 mm and a shock wave, associated with the initial rapid expansion, was observed. When breakdown occurred, the main spark channel always followed the track of the leader. Therm...
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A simplified analytical model of a high-current SF arc in an axial gas blast is presented. The model predictions of axially distributed temperature, radius and voltage are compared with experimental data for a particular interrupter geometry and static-pressure operating conditions. The equilibrium arc temperature is established by equating the optically thick radiation density to the total convec...
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